Table 3.

Cost-Effectiveness Results in Base Case Model (WTP Threshold = $150,000)

Tests	Total QALYs per 1000 patients	Total costs per 1000 patients, 2017 US$	Test comparisons*	ICER (cost per additional QALY gained)	INMB (per 1000 patient)	INMB (in the US 65-year-old cohort with diarrhea)
NAAT alone	13,592.86	$2,538,601	NAAT alone vs. GDH/NAAT	$54,547	$481,627	$41,242,471
GDH/NAAT	13,587.81	$2,263,377	NAAT alone vs. GDH/EIA	$55,410	$487,215	$41,720,978
GDH/EIA	13,587.71	$2,253,197	NAAT alone vs. NAAT/EIA	$50,231	$519,132	$44,454,027
NAAT/EIA	13,587.66	$2,277,229	GDH/NAAT vs. GDH/EIA	$96,841	$5588	$478,508
			GDH/NAAT vs. NAAT/EIA	NAAT/EIA dominated†	$37,504	$3,211,556
			GDH/EIA vs. NAAT/EIA	NAAT/EIA dominated†	$31,916	$2,733,049

QALY quality-adjusted life year, WTP willingness to pay, ICER incremental cost-effectiveness ratio, INMB incremental net monetary benefit; NAAT nucleic acid amplification test, GDH glutamate dehydrogenase, EIA enzyme immunoassay

*NAAT alone vs. NAAT/EIA = (NAAT costs − NAAT/EIA costs) / (NAAT QALYs − NAAT/EIA QALYs). NAAT alone vs. GDH/EIA = (NAAT costs − GDH/EIA costs) / (NAAT QALYs − GDH/EIA QALYs). NAAT alone vs. GDH/NAAT = (NAAT costs − GDH/NAAT costs) / (NAAT QALYs − GDH/NAAT QALYs). GDH/NAAT vs. GDH/EIA = (GDH/NAAT costs − GDH/EIA costs) / (GDH/NAAT QALYs − GDH/EIA QALYs)

†Implies greater cost and less effectiveness; compared with GDH/NAAT and GDH/EIA, NAAT/EIA dominated